The present invention relates to machine tools in general, especially to grinding machines, and more particularly to improvements in machine tools of the type wherein the holder or holders for one or more material removing or other work treating tools are surrounded by protective enclosures in the form of hoods or the like to prevent injury to attendants and/or contamination of the area around the machine. For example, such hoods are often used to confine the grinding wheel or wheels on the rotating spindle or spindles of a grinding machine in order to avoid propulsion of removed particulate material and/or spraying of a coolant or other liquid media into the area around the grinding machine.
If a grinding machine is equipped with a tool changing device, e.g., a device which can automatically or otherwise remove a grinding wheel from the spindle and replace it with one of several spare grinding wheels which are stored in a suitable magazine, the protective enclosure for the grinding wheel on the spindle must be shifted, pivoted or otherwise moved out of the way in order to afford access to the grinding wheel for the purpose of detachment from the spindle as well as to provide room for attachment of a fresh grinding wheel. This means that the space which must accommodate the enclosure during replacement of a grinding wheel remains unoccupied at all times except for the short interval which is required for an exchange of grinding wheels. On the other hand, an enclosure is necessary and is normally required in such types of machine tools for the sake of safety.